< objective-c > Protocols, Reflections and categories

Protocol (@protocol): interface equivalent to Java

Protocol methods are not necessarily implemented, you can use @required and @optional to set, the default is @required (ob is weak syntax, even if you do not implement the required method compile run will not error)

Reflection of Class

Common methods

Class variable name = [Class or object class];

Class variable name = [Class or object superclass];

Class Variable name = nsclassfromstring (string of method name);

NSString * Variable name = Nsstringfromclass (class type parameter);

Instantiating an object as a string of a class name

Class = nsclassfromstring (@ "Student"); ID obj = [[class  alloc]init]; NSLog (@ " created object:%@", obj)

The introspection method provided in NSObject

-(BOOL) Iskindofclass: (Class) AClass determines whether the object belongs to the specified type or its subclasses

-(BOOL) Ismemberofclass: (Class) AClass determines whether the object is of a specified type

-(BOOL) Issubclassofclass: (Class) AClass determines whether the object is a subclass of the specified type

-(BOOL) Conformstoprotocol: (Protocol *) Aprotocol determines whether a class/object implements a protocol (parameters are passed in using @protocol (MyProtocol))

Category: How to add a new method to an existing class

Category declarations for categories

@interface ClassName (CategoryName)

-(void) addmethod;

@end

Category implementations

#import "Classname+categoryname.h"

@implementation ClassName (CategoryName)

-(void) Addmethod {

Add code to implement the method;

}

@end

Benefits of the Category

Want to extend the classes provided by the framework (no source code)

If you do not want to generate a new subclass, such as an extension to Nsarray

Easy to do project management, can be a source (non-extended Class) in multiple places to share, multi-person collaborative development

Seamless expansion of the system framework

< objective-c > Protocols, Reflections and categories